IBM 350 RAMAC Disk File - Mountain View, California
Posted by: 
DougK
N 37° 24.836 W 122° 04.646
10S E 581640 N 4141191
The IBM 350 RAMAC actuator and disk stack was the world's first hard disk drive. It has fifty 24 inch disks that rotate at 1,200 RPM and holds 5 million characters of information.
Waymark Code: WMNHYZ
Location: California, United States
Date Posted: 03/20/2015
Views: 3
RAMAC stands for "Random Access Method of Accounting and Control."
This is the world's first hard disk drive. It was built in 1956 by IBM engineers at their Cottle Road development center in San Jose, California.
Wikipedia states:
The 350 stored 5 million 6-bit characters (3.75 MB). It had fifty 24-inch (610 mm) diameter disks with 100 recording surfaces. Each surface had 100 tracks. The disks spun at 1200 RPM. Data transfer rate was 8,800 characters per second. An access mechanism moved a pair of heads up and down to select a disk pair (one down surface and one up surface) and in and out to select a recording track of a surface pair. Several improved models were added in the 1950s. The IBM RAMAC 305 system with 350 disk storage leased for $3,200 per month. The 350 was officially withdrawn in 1969.
U.S. Patent 3,503,060 from the RAMAC program is generally considered to be the fundamental patent for disk drives. This first-ever disk drive was initially cancelled by the IBM Board of Directors because of its threat to the IBM punch card business but the IBM San Jose laboratory continued development until the project was approved by IBM's president.
The 350's cabinet was 60 inches (152 cm) long, 68 inches (172 cm) high and 29 inches (74 cm) wide.
The RAMAC unit weighed over a ton, had to be moved around with forklifts, and was delivered via large cargo airplanes.
The RAMAC now resides at the Computer History Museum in Mountain View, California.
The 350 RAMAC Disk File was designated an International Historic Landmark by the American Society of Mechanical Engineers on February 27, 1984.
ASME document: (PDF)